This is from my experience for the last 45 years in the corporate world evaluating guys like you. I was in charge of purchasing, hiring workers, and subcontracting work before I retired:
You must get yourself in front of the appropriate people.
Look and act like a professional before you walk in, while you are there, and after you walk out of the business's front door. The first impression of you is important. If you are driving your work vehicle or personal vehicle, make sure it is clean and the equipment you are hauling looks good. Do not show up with teenage boys under 18, because they will not be allowed to perform that work, due to OSHA regulations in commercial situations (it is the same in residential and you may get by until someone gets hurt, then you then will pay dearly). Ask for the person who is responsible for building maintenance. If the people occupying the building are renting, not the owner, you might ask who is the owner and go there if the owner maintains the property. Odds are you will get turned down more than once, but go back again. Being persistent pays off. If the business is a church, you should expect to go to some committee meeting in the evening for an interview. Leave a couple of clean professional looking business cards and a couple advertisements (fliers) each time you visit. When you finally get to talk to someone, ask them for the opportunity to bid the next time they are ready to negotiate their exterior maintenance contract (be specific that you want to do their yard work). Usually companies do a contract once per year. Be ready to present business references if asked (a resume for you, showing your business experience is what they will want). Ask them if they will share with you their invitation to bid from last time. If they have an invitation they send out, it will list each thing they expect you to provide, so you will know what to expect. If they do not have an invitation, ask them specifically what they expect, and take notes so you will not miss anything. An incomplete proposal will get thrown in the trash.
You will be required to have both liability and workman's compensation insurances. They most likely will ask for a certificate of insurance from your agent, proving you are insured, before allowing you to bid. If you claim to be a business you will be required to have a federal ID number for tax purposes, before you get paid.
A business client may ask you about your insurance modification number. (talk to your insurance agent) A business client may ask you about your written safety plan. A business client may ask you about your written drug prevention plan and your policy of how you deal with problems. You will be required by law to keep records at your workplace office for OSHA. You will be required by law to keep a MSDS log that includes a sheet for each hazardous product you have in your possession in the work place. You may be ask how you recycle waste products, green is good. You may be asked if you or your partners are a minority (your wife as a business partner may enhance your chances). You will be required by law to keep records that you have trained all employees in the safe and proper way to operate the equipment you allow them to operate. You will be required by law to post legal notices at a location that all employees can read them. It goes on and on............
Usually businesses not only want someone to mow, trim, and blow, they most likely will want someone to maintain flowers, shrubs, and trees. They might expect that person to fertilize, mulch, prune, aerate, seed, etc, at a specified time (once or twice) each year. Sometimes picking up trash, snow removal, storm damage cleanup, or the like is included or might be at an additional unit cost. (hourly or per each occurance). You might have to include hauling the debris away and pay the dump fees. If they do not have an invitation explaining what they want, you should prepare a proposal that shows them what you can do, and how much it costs. The more information you give the better. Make your proposal pretty and professional. Read it twice and then have some else read it for you to check for errors and bad grammar, before you give it to a potential client. You will only get one shot. No matter how good you are at mowing, that is not what will get you that commercial job. Being prepared to provide what the client wants and being professional while you do it is what it takes.
When you are adding up your costs to bid, do not forget that you, as the employer for anyone working under you, will be responsible for paying, in addition to their wages, 50% of their social security plus medicare tax, and 100% of their insurances that are required by law. An additional 30% to 35% is normal overhead to cover those expenses. If you provide benefits to your workers, overhead could be 40% or more. That overhead is in addition to your cost of wages, fuel, material, equipment, equipment maintenance, business expenses, and taxes. What is left after you pay everything, including yourself, is profit.
Do not expect to get paid each time you finish work. It will not happen in the business world. Hope to get paid once a month. After you complete your work, you will have to send an invoice. You should get paid within 30 days after you send the invoice. It takes some time for the client to process the invoice and send out a check. Sometimes a business runs short of cash because they did not get paid by their client. Sometimes the check will come on time. Sometimes it will not and you will have to go chase your client to get your payment. You will need to have enough cash upfront to pay wages and cover expenses until the check comes. Your expenses go on and on, no matter if you are paid on time or not.
As you can see, commercial mowing is not like stopping by and mowing someone's home lawn once per week where they give you cash.
The professional lawn care people in my area are really struggling. Too many just starting out do not understand their real costs, until they are in too deep. Also, there are more inexperienced people trying to find work and wanting to mow than there are lawns to mow. Therefore profits are low or none for the pro's. Most are working for low wages, barely or not actually covering expenses, and no to low profit. Hope it is better where you are!
Hope this helps!